For human beings, mosquitoes are the most dangerous animals in the world. The microbes they transmit kill millions of people every year, even more than the human race’s second-most deadly predator—other humans.
During mosquito season, you could cover yourself with clothing from head to toe every time you go out, douse yourself with insect repellent every day or just never go outside…but that’s no way to live, and you still might get bit.
Much better: The more you know about mosquitoes, the better you’ll be able to avoid their bites—or recognize symptoms of the diseases they carry so that you can act quickly when they do bite you.
They’re Out for Blood
Mosquitoes use a variety of senses to find their prey. First, they detect and follow from more than 160 feet away the plumes of carbon dioxide we exhale every few seconds. Once they get within a range of about 15 to 50 feet, hungry mosquitoes see their targets for the first time. When they are within striking distance, mosquitoes use moisture, heat and odor sensors to find the most suitable place to do what they came to do—drink your blood.
After detecting the areas where capillaries are closest to the skin’s surface, a mosquito uses a serrated probe to insert two tubes. The first tube injects you with saliva, which serves two purposes—it acts as an anesthetic so that you don’t feel the mosquito breaking your skin, and it prevents your blood from immediately clotting. It is the saliva that causes the allergic reaction that makes mosquito bites itch.
The other tube sucks blood out of you and into the mosquito’s midgut.
Steps to Protect Yourself
The surest way to avoid mosquito bites is to stay indoors. But since never going outside isn’t a realistic way to live, it’s important to understand how to avoid bites when you do leave the house.
There is a common misconception that mosquitoes bite only around dawn and dusk. Although it’s true that many mosquito species are most active during and after sunset and sunrise, some other species feed during the day. Therefore, no matter when you are outside during the spring-to-fall mosquito season, assume that hungry mosquitoes are using your breath to lock in on your position the second you step outside.
And yes, it’s true that mosquitoes prefer to bite certain people and even animals over others. Even after exhaustive experimentation, science has not yet been able to figure out exactly why some people are more attractive to mosquitoes than others. If you know that mosquitoes like you, take extra precautions.
Wear lightweight, long-sleeved shirts and pants, even on hot days. The less skin you leave exposed, the less surface area mosquitoes have to bite. (That may seem obvious, but how often do you see people outside on a coolish night dressed in shorts and polos and getting bit when long clothing would be perfectly comfortable?) Because mosquitoes can bite through thin clothing, somewhat loose-fitting clothing (not clinging to your skin) is the most protective.
If you’re going camping or hiking, or if you plan to otherwise spend extended periods outside in mosquito-prone areas, you can treat your clothing with an EPA-registered insecticide such as permethrin for added protection. Permethrin, is a different chemical than those found in sprays and creams meant for use on skin. Brands such as Repel and Sawyer offer permethrin-based clothing spray, and some companies, such as L.L.Bean and ExOfficio, sell clothing that is pretreated with permethrin.
For any exposed body parts, use an EPA-approved repellent that’s meant for skin—see below for how to choose.
Tip: If you’re using sunscreen, the CDC recommends applying the sunscreen first, then the bug spray because sunscreen may not be able to soak into the skin through a film of insect repellent. Also, keep in mind that insect repellent can diminish the effectiveness of sunscreen, so if you’re applying both, consider a higher SPF than you would normally use.
Choosing the Right Repellent
The EPA maintains a tool to help people find the right repellent to use. In most cases, the chemical DEET is the most effective option for repelling mosquitoes (and other bugs such as ticks and leeches). DEET, unfortunately, suffers from as a perception problem. That’s likely because it often is confused with DDT, which is a banned mosquito insecticide that was proved to be harmful. Popular Science cites at least 20 years of major studies that prove DEET is safe to use as directed even for women who are pregnant or breastfeeding. The CDC agrees.
About 120 EPA-registered DEET products are offered by roughly 30 companies. Look on the label for either the common shorthand DEET or the full chemical name, N,N-diethyl-m-toluamide. Most products contain between 10% and 30% DEET. The higher the concentration, the longer it lasts, with 10% considered effective for two hours and 24% considered effective for five hours. According to the EPA, DEET is safe for children of all ages and with no restriction in the percentage of DEET in the product. The American Academy of Pediatrics, however, suggests using products that contain DEET in concentrations no greater than 30% when spraying children.
Tip: Some plants contain natural mosquito repellents, and planting them in commonly used areas outside your home may reduce your exposure to mosquitoes when you spend time in your yard, on your porch or on your deck. Try planting catnip, lavender, marigolds, citronella grass, rosemary, scented geraniums and/or basil.
Keep in mind that mosquitoes thrive in standing water. Check your property, and remove all standing water in and around your yard—think empty flower pots, watering cans or children’s toys—and check for more after it rains. Poorly maintained swimming pools or hot tubs can produce thousands of mosquitoes.
The Zika and West Nile Threats
There are thousands of species of mosquitoes in the world, hundreds of which prowl for blood in the US. Only a handful of them can transmit viruses, but that’s enough to endanger people in virtually every area of the country, both rural and urban.
Unlike many developing countries, in recent years the US has been spared deadly mosquito-borne pandemics such as malaria, dengue fever and yellow fever.
Although malaria was eradicated in the US the early 1950s, about 1,700 cases are imported into the US every year by travelers. Experts fear that recent outbreaks of Zika, chikungunya and yellow fever viruses in Brazil and other parts of Latin America could be carried to the US through infected travelers, where it could then be spread by local mosquitoes. It is much more likely, however, that people in the US will contract West Nile virus from infected mosquitoes.
First detected in North America in 1999, West Nile unexpectedly swept across the US by 2003 and is now present in every continental state. Since many people who become infected don’t display symptoms, or they display symptoms that mimic the flu, illness from West Nile virus infection often is misdiagnosed or not reported at all. It is likely that there actually are 10 times the reported number of cases each year.
There are far fewer reported cases of Zika, just 5,413 as of August 9, 2017. All but a few hundred were acquired outside the US and imported by recent travelers. Like West Nile, Zika infections are rarely fatal, but there is no cure yet and no vaccine. Infection is especially hazardous to pregnant women, who can pass Zika on to their fetuses. Severe birth defects also have been associated with the virus, including microcephaly, a condition in which babies are born with heads (and in many cases brains) that are smaller than those of healthy babies. Congenital Zika syndrome can lead to babies being born with damaged eyes, joints or muscles, or even with severe microcephaly, where the skull is partially collapsed.
How to Check for Updates
The CDC is an important source of information about mosquitoes and the diseases they carry. But people should supplement that information with news from their local governments. Local agencies tasked with managing and monitoring mosquitoes and mosquito-borne illnesses release targeted—in some cases block-by-block—updates about the threats in the area.
Do an online search with your municipality’s name and the word “mosquito” to find the local agency that tracks and manages mosquitoes and the viruses they carry. If you discover that your area currently is high-risk for West Nile virus, stay indoors whenever possible, especially at and just after dusk. When you do go out, take extra precautions such as treating your clothing.